1. Field of the Invention
The present invention relates to a microwave oven, and more particularly to an apparatus for and a method of detecting a food weight in a microwave oven.
2. Description of the Prior Art
A conventional technique for detecting the weight of a food to be heated in a microwave oven has been disclosed in Korean Patent Publication No. 90-2322 (Application No. 85-8278).
In accordance with the conventional technique, sensors constituted by piezoelectric elements are placed on a rotation track of a support roller mounted at a peripheral edge of a rotation ring adapted to support and rotate a turntable. As a food is heated, the rotation ring rotates, thereby causing the support roller to press the sensors. Each sensor generates a voltage varied depending on the weight of the food to be heated. Based on the voltage, the food weight can be detected.
In this conventional technique for detecting the food weight by use of the sensors constituted by the piezoelectric elements, however, the voltage generated from each sensor is nonlinearly varied depending on the food weight. This results in a difficulty to accurately detect the food weight. Furthermore, this technique requires the use of a look-up table previously stored with weights respectively corresponding to various voltages generated from sensors. The voltage generated from each sensor may be also varied depending on an installed condition of the sensor and variations in ambient temperature and humidity, thereby resulting in a high error generation rate. In addition, the sensors may be easily damaged due to the food weight applied thereto.
When a drive motor is stopped after completion of the cooking of the food, the rotation of the support roller is stopped. However, if the support roller is stopped on a sensor, the weight of the turntable is applied to the sensor, thereby causing the sensor to be deformed. Such a deformation of the sensor may result in a degradation in accuracy. Moreover, the sensor may be damaged when the stopped state of the support roller is kept for a long time or another load is placed on the turntable.